Thanks,
I'll drain the oil and see if it's been overfilled. I don't recall putting any additional oil in since I changed it's oil. I kept the small oil bottle that they provided with the mower when it was new and marked where the fill line was so I can add back what it takes. Barring that...
I have an ~4 year old Murray push mower with a B&S 500 Series engine. Model 9P602 0019 F1. After the last mow, I noticed some oil dripping from under the air breather, but did not think anything of it. My next mow I looked down and there was a patch of brown sludge under the air breather...